1. Field of the Invention
This invention relates to liquid leak detectors. More specifically, this invention relates to a liquid leak detector disposed to optically measure changes in the volume of liquid stored within a container.
While the present invention is described herein with reference to a particular embodiment, it is understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional embodiments within the scope thereof.
2. Description of the Related Art
Leak detectors are utilized in many applications of which underground chemical storage tanks is one example. Leak detectors are typically disposed to estimate changes in the volume of liquid held within a tank by measuring the time rate of change of the liquid level therein. One technique for measuring the time rate of change of liquid level involves monitoring the pressure change at the bottom of the tank. However, this technique is not of the requisite precision to discern the existence of certain "slow" leaks. The capability to detect such small leaks is of particular importance when monitoring tanks containing toxic liquids.
In a second technique an electro-mechanical apparatus is operative to determine the time rate of change of liquid level within the tank. A float element residing on the surface of the liquid changes the position of a contact on a resistance wire as the fuel level changes. The equivalent resistance may be periodically measured to determine the rate of change of the liquid level. Such leak detectors are inaccurate, and include mechanical parts subject to attrition over time.
In a third leak detection technique, changes in the volume of a sample quantity of liquid included within the tank are monitored. This volumetric method is somewhat more accurate than the techniques described above, and may be employed to discern leak rates of approximately 0.05 gallons/hour. Unfortunately, this technique is expensive and can take up to six hours to perform. These drawbacks make the volumetric method impractical for daily testing which, in the context of toxic liquid storage, may be imperative.
Hence, a need in the art exists for an inexpensive, leak detector free of moving mechanical parts which allows precision measurements to be conducted in a relatively short time interval.